FIG. 1 illustrates a respiratory mask produced by ResMed including a forehead support (e.g., see U.S. Pat. No. 6,532,961). The ResMed forehead support has two primary functions. The first primary function is to stabilize the cushion on the patient's face to facilitate a seal. The forehead support mainly acts to prevent axial rotation about the horizontal and median axes as shown in FIG. 1.
The second primary function is to correctly locate the cushion against the patient's facial profile, again facilitating the generation of a seal. In prior forehead supports produced by ResMed, the two variables controlled by the forehead support are the displacement of the cushion (depicted by X in FIG. 2a) in the horizontal plane and also the angle (depicted by θ in FIG. 2a) of the cushion's sealing surface to the frontal plane. FIGS. 2a to 2c illustrate alternative positions of the forehead support to vary the displacement and angle of the cushion. By allowing variations in the displacement and angle of the cushion, a compromise between generation of a seal and prevention of excessive force on sensitive areas, such as the nasal bridge, can be achieved, thus maximizing patient comfort.
Adjustment of the displacement and angle can also be used to maximize the contact area between the forehead support and the patient's forehead. By maximizing the contact area, the overall force on the patient's forehead may be reduced, which improves patient comfort.